The present invention relates to a soldering method, a soldering device, and a method and a device of fabricating an electronic circuit module.
A method of bonding a plurality of electronic parts to an interconnect substrate by combining reflow soldering and flow soldering is known. In this case, one surface of the interconnect substrate is generally subjected to reflow soldering, and the other surface is subjected to flow soldering thereafter.
In recent years, it is desired that the electronic parts be mounted using solder containing no lead. However, since electrodes of the electronic parts are generally plated with a material containing lead, a metal layer containing lead may segregate in solder joint sections at the boundary with the interconnect substrate after reflow soldering. Since the metal layer containing lead has a melting point lower than that of the metal layer containing no lead, the solder joint sections of the electronic parts mounted on one surface of the interconnect substrate may be removed from the interconnect substrate as a result of heat applied from the other surface during flow soldering.
According to a first aspect of the present invention, there is provided a soldering method comprising the steps of:
bonding a first electronic component having electrodes plated with a material containing lead to one surface of an interconnect substrate through solder containing no lead;
flow-soldering to bond a second electronic component to the other surface of the interconnect substrate; and
heating a joint section between the first electronic component and the interconnect substrate at the same time as or after the step of flow-soldering to melt the joint section.
According to a second aspect of the present invention, there is provided a method of fabricating an electronic circuit module, wherein the first and second electronic components are mounted on the interconnect substrate by the above soldering method.
According to a third aspect of the present invention, there is provided a soldering device comprising:
a flow soldering section, when a first electronic component having electrodes plated with a material containing lead is bonded to one surface of an interconnect substrate through solder containing no lead, bonds a second electronic component to the other surface of the interconnect substrate,
wherein the flow soldering section includes a heater disposed on the side of a surface of the interconnect substrate to which the first electronic component is bonded, to melt a joint section between the first electronic component and the interconnect substrate.
According to a fourth aspect of the present invention, there is provided a device of fabricating an electronic circuit module comprising the above soldering device, wherein the first and second electronic components are mounted on the interconnect substrate.